Stimulator leads and methods for lead fabrication

ABSTRACT

A lead for a stimulation device can include an array of electrodes with each electrode having a front surface and a back surface; a plurality of conductors; a carrier formed around the array of electrodes; and a biocompatible material that may be disposed over and/or joined with the carrier and the back surfaces of the electrodes. A conductor is attached to the back surface of each electrode. The carrier can be formed around the array of electrodes, but does not completely cover the front surface or back surface of the electrodes.

FIELD OF THE INVENTION

The invention is directed to stimulators and stimulator components andmethods of making the devices. The invention is also directed tostimulators and stimulator components with electrodes located in acarrier, as well as methods of making the devices.

BACKGROUND OF THE INVENTION

Stimulators have been developed to provide therapy for a variety ofdisorders, as well as for other treatments. For example, stimulators canbe used in neurological therapy by stimulating nerves or muscles, forurinary urge incontinence by stimulating nerve fibers proximal to thepudendal nerves of the pelvic floor, for erectile and other sexualdysfunctions by stimulating the cavernous nerve(s), for reduction ofpressure sores or venous stasis, etc.

As one example, spinal cord stimulation is a well accepted clinicalmethod for reducing pain in certain populations of patients. Stimulatorshave been developed to provide therapy for a variety of treatments. Forexample, stimulators can be used to stimulate nerves, such as the spinalcord, muscles, or other tissue. A stimulator can include a controlmodule (with a pulse generator), one or more leads, and an array ofstimulator electrodes on each lead. The stimulator electrodes are incontact with or near the nerves, muscles, or other tissue to bestimulated. The pulse generator in the control module generateselectrical pulses that are delivered by the electrodes to body tissue.As an example, electrical pulses can be provided to the dorsal columnfibers within the spinal cord to provide spinal cord stimulation.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, a method of making a lead for a stimulation deviceincludes forming an array of electrodes in a pre-determined arrangement.A carrier is formed around the array of electrodes to maintain thearrangement. A biocompatible material is disposed over at least aportion of the carrier to form an array body that includes the array,the carrier, and the biocompatible material.

In another embodiment, a lead for a stimulation device includes an arrayof electrodes; a plurality of conductors; a carrier formed around thearray of electrodes; and a biocompatible material disposed over, and incontact with, the carrier and the back surfaces of the electrodes. Theelectrodes have a front surface and a back surface, and a conductor isattached to the back surface of each electrode. The carrier is formedaround the array of electrodes, but does not completely cover the frontsurface or back surface of the electrodes. The biocompatible materialand the carrier may be different, e.g., of different materials or thesame material but having different durometers (hardness) or they may beexactly the same material but joined together during the manufacturingprocess.

In another embodiment of the invention, a system for stimulationincludes an electronic subassembly, a lead, and a plurality ofconductors. The lead includes an array of electrodes with each electrodehaving a front surface and a back surface; a carrier formed around thearray of electrodes but not completely covering the front surface orback surface of the electrodes; and a biocompatible material disposedover, and in contact with, the carrier and the back surface of theelectrodes. The carrier and the biocompatible material are different.The conductors are attached to the back surface of each electrode andcouple the electrodes to the electronic subassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the present invention aredescribed with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified.

For a better understanding of the present invention, reference will bemade to the following Detailed Description, which is to be read inassociation with the accompanying drawings, wherein:

FIG. 1 is a schematic perspective view of one embodiment of an array ofelectrodes positioned within a carrier mold, according to the invention;

FIG. 2 is a schematic cross-sectional view of the array of electrodespositioned within the carrier mold of FIG. 1;

FIG. 3 is a schematic cross-sectional view of one embodiment of an arrayof electrodes positioned within a carrier mold and having a carrier moldcover over the carrier mold, according to the invention;

FIG. 4 is a schematic cross-sectional view of one embodiment of an arrayof electrodes positioned within a carrier mold, with a carrier moldcover over the carrier mold and a carrier molded around the array ofelectrodes, according to the invention;

FIG. 5 is a schematic perspective view of one embodiment of the topportion of an array of electrodes with a carrier formed around thearray, according to the invention;

FIG. 6 is a schematic perspective view of one embodiment of the bottomportion of the array of electrodes of FIG. 5, according to theinvention;

FIG. 7 is a close-up schematic perspective view of the bottom portion ofthe array of electrodes of FIG. 6, according to the invention;

FIG. 8 is a schematic perspective view of one embodiment of the top ofan array body comprising an array of electrodes, a carrier formed aroundthe array, and a biocompatible material, where the biocompatiblematerial does not increase the width of the array body as compared tothe width of the carrier;

FIG. 9 is a schematic perspective view of one embodiment of the top ofan array body comprising an array of electrodes, a carrier formed aroundthe array, and a biocompatible material, where the biocompatiblematerial increases the width of the array body as compared to the widthof the carrier;

FIG. 10 is a schematic cross-sectional view of the array body of FIG. 9at line 10-10;

FIG. 11 is a schematic exterior perspective view of one embodiment of astimulator system, according to the invention; and

FIG. 12 is a schematic overview of components of a system forstimulation, according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to stimulators and stimulator components andmethods of making the devices. The invention is also directed tostimulators and stimulator components with electrodes located in acarrier, as well as methods of making the devices.

Examples of stimulators are found in U.S. Pat. Nos. 6,181,969;6,516,227; 6,609,029; 6,609,032; and 6,741,892; and U.S. patentapplication Ser. No. 11/238,240, all of which are incorporated byreference.

In some designs of stimulators, electrodes are presented on a lead.Examples of leads include, for example, percutaneous leads and paddleleads. It is generally desirable that the electrode (or electrodecontacts) of such stimulators are reproducibly located on the lead, withsurface areas exposed to the tissue to be stimulated. Making such leadsmay become difficult when the electrodes are small and/or a large numberof electrodes are needed. A reliable method of holding the electrodes inthe desired position during the process of forming the lead isdesirable.

In at least some applications, it is desirable that the electrode(s) ofa stimulator be located and secured in position during the process ofmanufacturing the stimulator. Methods of locating and securing theposition of the electrode(s) during the manufacturing process have beendescribed, for example, in U.S. Pat. No. 6,757,970, which is hereinincorporated by reference. One conventional method of positioningelectrodes during the manufacturing process involves using a metal foilcarrier or stamped iron plate as a temporary carrier to which theelectrodes are affixed during the process of forming the lead. Thetemporary carrier is then typically removed using an etching process.Such a method of using a temporary metal foil that is later etched awayto make an electrode array is described in U.S. Pat. No. 6,038,484.

The etching process often involves chemical etching, and in at leastsome instances an acid mixture. The process of chemical etching mayresult in a longer manufacturing cycle time, as it includes apost-etching soaking and drying treatment. Use of an acid mixture mayalso pose safety hazards during the manufacturing process. Fumes fromthe acid mixture may also discolor elements of the lead, such aspolyurethane tubing.

In at least some applications, it is desirable to manufacture a lead fora stimulator that does not include removal of a temporary carrier thatpositions electrodes during the manufacturing process. In someinstances, such a manufacturing method may result in savings of time,money, or operator oversight. For example, a method of making a lead caninclude positioning electrodes in a carrier that becomes part of thefinal product, thereby avoiding a process for removing a temporarycarrier.

Referring to FIG. 10, one example of a method of making a lead for astimulation device includes forming an array of electrodes 154 in apre-determined arrangement, forming a carrier 132 around the array, andplacing a biocompatible material 148 over at least a portion of thecarrier 132. In this method, an array of electrodes 154 is formed in apre-determined arrangement in an array body 104. The electrodes 154 canbe made using any conductive material. Examples of suitable materialsinclude, for example, metals, alloys, conductive polymers, andconductive carbon. The number of electrodes 154 in the array ofelectrodes 154 may vary, depending on the application for which theelectrodes 154 will be used (e.g., brain stimulation, neuralstimulation, spinal cord stimulation, etc.). For example, there can betwo, four, six, eight, ten, twelve, fourteen, sixteen, or moreelectrodes 154. As will be recognized, other numbers of electrodes 154may also be used.

The arrangement of the electrode(s) 154 may vary. For example, theelectrodes 154 may be arranged in a paddle type array, in which theelectrodes are arranged in two or more parallel columns, as illustratedschematically in FIGS. 5, 6, 8 and 9. The columns of electrodes can bealigned or staggered from one another, or in any other desired column orrow arrangement. The electrodes may also be arranged, for example, in arow, or “in line,” along the longitudinal axis of a small diameter leadbody. Optionally, the electrodes may be placed linearly, circularly, orelliptically. The arrangement of electrodes may be symmetrical orasymmetrical. As will be recognized, other arrangements of electrodesare also possible.

In one embodiment, the electrodes 154 are placed in the desired arrayarrangement by positioning the electrodes in a carrier mold 142 asillustrated schematically in FIG. 2. Suitable materials for the carriermold 142 include, but are not limited to, metal, wax, wood, polymers(including plastics), paper, composite materials, and the like.Preferably, the carrier mold 142 is made of a durable material thatallows the carrier mold 142 to be reused.

In one embodiment, the carrier mold 142 includes electrode positioningfeatures 144 a, e.g., indentations or depressions in the carrier mold142, that are disposed in the desired array arrangement. The electrodepositioning features 144 a aid positioning of the electrodes 154 in thepre-determined arrangement. For example, the electrodes 154 may beplaced in a carrier mold 142 that has indentations in the bottom of themold that accommodate the shape of the electrodes 154 and keep theelectrodes 154 in position during the process of manufacturing thecarrier 132. For example, the electrodes 154 may be concave and thecarrier mold 142 may have indentations that accommodate the concaveshape of the electrodes 154. Preferably, at least a portion of the sidesurface of the electrodes 154 remains exposed within the carrier mold142.

Electrode positioning features 144 a can also include, for example,depressions, protrusions, extensions or any other feature that aidspositioning of the electrodes 154. For example, the carrier mold 142 mayhave protrusions from the bottom of the mold upon which a concaveelectrode surface can sit. Optionally, the position of the electrodes154 in the carrier mold 142 may be further secured using a vacuum table.

After the electrodes 154 are positioned in the carrier mold 142, acarrier mold cover 146 is placed over the electrodes 154 and the carriermold 142. FIG. 3 illustrates schematically a cross-sectional view of oneembodiment of an array of electrodes 154 positioned within a carriermold 142 with a carrier mold cover 146. Suitable materials for thecarrier mold cover 146 include, but are not limited to, metal, wax,wood, polymers (including plastics), paper, composite materials, and thelike. Preferably, the carrier mold cover 146 is made of a durablematerial that allows the carrier mold cover 146 to be reused. It will berecognized that the array of electrodes 154 may be formed in apre-determined arrangement either before or during the process offorming a carrier 132 around the array of electrodes 154.

In one embodiment, the carrier mold cover 146 also has electrodepositioning features 144 b. As illustrated in FIG. 3, in one embodiment,the carrier mold cover 146 has electrode positioning features 144 b thatare protrusions that fit within a portion of the electrode 154. Theelectrode positioning features 144 b could also be depressions.Optionally, the carrier mold cover 146 protects at least one surface ofthe electrode 154 from coverage by a carrier material during the processof forming the carrier 132 (FIG. 4) around the array of electrodes 154.For example, the carrier mold cover 146 may be designed such that itprevents or reduces contact or coverage of at least one surface 160 ofthe electrode 154 with the carrier material during the process offorming the carrier around the electrodes 154 (FIG. 3). The protectedportion of the surface 160 of the electrode 154 may be used, forexample, to connect to components of the electrical circuitry. In oneembodiment, a carrier mold cover 146 that prevents or reduces contact ofone surface 160 of the electrode 154 with the carrier material isillustrated schematically in FIGS. 3 and 4. In other embodiments, onlyone of the carrier mold 142 and carrier mold cover 146 includeselectrode positioning features 144 b.

The carrier 132 is then formed around the array of electrodes 154 asillustrated in FIG. 4. The carrier 132 can be made of any biocompatiblematerial including, for example, silicone, polyurethane,polyetheretherketone (PEEK), epoxy, and the like.

The carrier 132 may be formed by any process including, for example,molding (including injection molding), casting, and the like. In oneembodiment, the carrier 132 is formed by injection molding. Preferably,when forming the carrier, the material of the carrier does not cover thetop surface 156, shown in FIG. 5, (or at least a substantial portion ofthe top surface 156) of the electrodes 154. Also, preferably, thecarrier material does not cover the bottom surface 158, shown in FIG. 6,(or at least a substantial portion of the bottom surface 158) of theelectrodes 154.

In one embodiment, the carrier mold 142 and carrier mold cover 146include one or more cooperating locating features 130 (FIG. 1) that aidproper alignment of the carrier mold 142 and carrier mold cover 146. Forexample, corresponding locating features may be a locating pin insertedinto a corresponding hole in a carrier mold 142. A locating pin may beinserted through two halves of a carrier mold to keep the two halvesaligned and held together.

A top view of the intermediate assembly 180, which includes thecompleted carrier 132 and the array of electrodes 154, is illustratedschematically in FIG. 5. A bottom view of the intermediate assembly 180,including the carrier 132 and array of electrodes 154, is illustratedschematically in FIG. 6. The carrier 132 may have any shape. Preferably,the carrier 132 is formed around the array of electrodes 154 so that atleast one surface, and more preferably both the top and bottom surfaces,of each electrode 154 in the array is exposed. The carrier is typicallysufficiently sturdy to maintain the arrangement of the electrodes 154during the remaining manufacturing steps.

After the carrier 132 is molded around the electrodes 154, conductors127 are joined to the electrodes 154 positioned in the carrier 132.Optionally, the intermediate assembly 180, which includes the completedcarrier 132 and the array of electrodes 154, can be removed from thecarrier mold 142 before the conductors 127 are coupled to the electrodes154. The carrier mold 142 may have a removable top plate that aids inremoving the intermediate assembly 180 from the carrier mold 142.

In one embodiment, the conductors 127 are attached to the electrodes 154as illustrated in FIG. 7. Preferably, conductors 127 are attached to theback side of the electrodes 154, which is the side of the electrode 154opposite the side that will be exposed to the body tissue. In anotherembodiment, the conductors 127 may be joined to the electrodes 154 priorto forming the carrier 132.

Optionally, the exposed surfaces (particularly the bottom surface 158)of the electrode(s) 154 may be cleaned after the carrier is formedaround the electrodes 154, but before the conductor(s) 127 are coupledto the electrode(s) 154. The electrode surfaces may be cleaned by anymethod including, for example, plasma etching, use of a solvent (e.g.,alcohols, organic solvents, etc.), and the like.

The conductors 127 can be made of any conductive material. Examples ofsuitable material for conductors 127 include, for example, metals,alloys, conductive polymers, and conductive carbon. In one embodiment,the conductors 127 are insulated by an insulating material except wherethe conductor 127 makes contact with the electrode 154. The insulatingmaterial may be any material that is a poor conductor of an electricalsignal, including, for example, Teflon™, non-conductive polymers, nylon,Mylar, and composite materials. The conductors 127 may be attached tothe electrodes by any method including, for example, resistance welding,laser welding, conductive epoxy, and the like. Preferably, theconductors 127 are attached to the electrodes 154 by a method thatresults in a durable attachment of the conductors 127 to the electrodes154 under expected usage conditions. The conductor 127 typicallytraverses the lead to its proximal end to couple the electrodes 154 to apulse generator (optionally, via other conductive contacts).

Optionally, after the conductors 127 are attached to the electrodes 154,an adhesive may be applied over at least a portion of the conductors 127and the electrodes 154. Suitable adhesives include, for example,silicones, epoxies, and acrylics. The adhesive may be applied using anymethod that results in adhesive being applied to the surface of theconductors and/or electrodes including, for example, spray coating,brush coating, dip coating, and the like. In one embodiment, theadhesive applied to the conductors 127 provides stress relief to theconductor/electrode attachment.

In one embodiment, after the conductors 127 are attached to theelectrodes 154, but before the biocompatible material 148 is disposed onthe carrier 132, a path for the conductors 127 along the carrier 132 isdetermined and the conductors 127 are optionally secured in position.The conductors 127 may be secured, for example, by an adhesive or byapplying tension to another end of the conductor 127. Suitable materialsfor the adhesive include, for example, silicones, epoxies, acrylics, andthe like.

A biocompatible material 148 is then disposed over at least a portion ofthe carrier 132. The biocompatible material 148 may be disposed over aportion of the carrier 132 by any method including, for example, spraycoating, brush coating, molding, and the like.

In one embodiment, the biocompatible material 148 is disposed over aportion of the carrier 132 by a molding process. The carrier 132 and anarray of electrodes 154 are placed face down into a mold (i.e., with thetop portion 134 of the intermediate assembly 180 down; with the surfaceof the electrodes 154 that will be exposed to the tissue facing down).Optionally, the mold has a shape that is complementary to the shape ofthe carrier 132. A cover is placed over the mold and the biocompatiblematerial 148 is added to the mold over the carrier 132. Thebiocompatible material 148 may be introduced to the mold by any methodincluding, for example, by injection. The biocompatible material 148 isthen allowed to harden, cure, or otherwise solidify.

Typically, the biocompatible material 148 covers the back surface 136 ofthe carrier 132 and increases the thickness of the array body 104, asillustrated in FIG. 10. The biocompatible material 148 typically coversthe back surface 158 of the electrodes 154 and the conductors 127 toform an insulating covering over the electrode/conductor connections. Insome embodiments, the biocompatible material 148 is disposed on thecarrier 132 such that the completed array body 104 has a width greaterthan the width of the carrier 132 as, for example, illustratedschematically in FIG. 9. Alternatively, the biocompatible material 148may be disposed on the carrier 132 such that the lead has a width equalto the width of the carrier 132 as, for example, illustratedschematically in FIG. 8.

The top surface 156 of the electrode(s) 154 may or may not extend abovethe surface of the array body 104. For example, the top surface 156 ofthe electrode(s) 154 may be flush with the surface of the array body104. Optionally, the top surface 156 of the electrode(s) 154 may extendbeyond the surface of the array body 104.

In one embodiment, the material used to form the carrier 132 and thebiocompatible material 148 are the same material. For example, both thecarrier 132 and the biocompatible material 148 could be silicone rubber.Alternatively, the material used to form the carrier 132 and thebiocompatible material 148 may be different. Preferably, thebiocompatible material 148 is capable of attaching to the carriermaterial without an additional adhesive. However, in some instances thecarrier 132 material may be covered by an adhesive prior to adding thebiocompatible material 148.

In at least some embodiments, the materials used to form the carrier 132and the biocompatible material 148 have different properties. Forexample, the carrier 132 material and the biocompatible material 148 mayhave a different durometer, hardness, flexibility, rigidity, density,elasticity, etc. In one embodiment, the carrier 132 material and thebiocompatible material 148 are the same material, but have differentproperties. For example, both the carrier 132 material and thebiocompatible material 148 can be made of silicone rubber, but thesilicone rubber used to form the carrier 132 material has a differentdurometer (e.g., a higher durometer) from the silicone rubber that isthe biocompatible material 148.

FIG. 11 illustrates schematically one embodiment of a stimulation system100. The stimulation system includes a control module (e.g., astimulator or pulse generator) 102, an array body 104, and at least onelead body 106 coupling the control module to the electrode array. Thearray body 104 and the lead body 106 form a lead. It will be understoodthat the system for stimulation can include more, fewer, or differentcomponents and can have a variety of different configurations includingthose configurations disclosed in the stimulator references citedherein. The formation of the array body 104 with the array of electrodes154, carrier 132, and biocompatible material 148 is described above. Thestimulation system or components of the stimulation system, includingone or more of the lead body 106, the array body 104 and the controlmodule 102, may be implanted into the body.

The control module 102 typically includes a housing 114 with anelectronic subassembly 110 and, in at least some embodiments, a powersource 120 disposed within a chamber in the housing. Preferably, thehousing is resistant to moisture penetration into the chamber containingthe electronic subassembly and power source. In some embodiments, watermay diffuse through the housing. Preferably, the diffused water isrelatively pure, without substantial ionic content, as deionized wateris relatively non-conductive.

The housing 114 may be made of any biocompatible material including, forexample, glass, ceramics, metals, and polymers. In one embodiment, thehousing 114 of the control module is formed of a plastic material thatresists the transport of moisture into the interior of the housing andis sufficiently sturdy to protect the components on the interior of thehousing from damage under expected usage conditions. Preferably, thematerial of the plastic housing is a hydrophobic polymer material. Thehousing 114 may include additives such as, for example, fillers,plasticizers, antioxidants, colorants, and the like. The thickness ofthe walls of the housing may also impact the moisture permeability ofthe housing. A minimum thickness needed to achieve a particular degreeof resistance to moisture transport will often depend on the materialselected for the housing, as well as any additives.

Optionally, the housing 114 can be covered, in full or in part, with acoating. The coating can be provided to improve or alter one or moreproperties of the housing 114 including, for example, biocompatibility,hydrophobicity, moisture permeability, leaching of material into or outof the housing, and the like. In one embodiment, a coating can beapplied which contains a compound, such as, for example, a drug,prodrug, hormone, or other bioactive molecule, that can be released overtime when the stimulator is implanted. (In another embodiment, thehousing itself may include such a compound to be released over timeafter implantation.)

FIG. 12 is a schematic overview of one embodiment of components of asystem for stimulation, including an electronic subassembly 110 (whichmay or may not include the power source 120), according to theinvention. It will be understood that the system for stimulation and theelectronic subassembly 110 can include more, fewer, or differentcomponents and can have a variety of different configurations includingthose configurations disclosed in the stimulator references citedherein. Some or all of the components of the system for stimulation canbe positioned on one or more circuit boards or similar carriers within ahousing of a stimulator, if desired.

Any power source 120 can be used including, for example, a battery suchas a primary battery or a rechargeable battery. Examples of other powersources include super capacitors, nuclear or atomic batteries,mechanical resonators, infrared collectors, thermally-powered energysources, flexural powered energy sources, bioenergy power sources, fuelcells, bioelectric cells, osmotic pressure pumps, and the like includingthe power sources described in U.S. Patent Application Publication No.2004/0059392, incorporated herein by reference.

As another alternative, power can be supplied by an external powersource through inductive coupling via the optional antenna 124 or asecondary antenna. The external power source can be in a device that ismounted on the skin of the user or in a unit that is provided near thestimulator user on a permanent or periodic basis.

If the power source 120 is a rechargeable battery, the battery may berecharged using the optional antenna 124, if desired. Power can beprovided to the battery 120 for recharging by inductively coupling thebattery through the antenna to a recharging unit 210 (see FIG. 12)external to the user. Examples of such arrangements can be found in thestimulator references identified above.

In one embodiment, electrical current is emitted by the electrodes 154to stimulate motor nerve fibers, muscle fibers, or other body tissuesnear the stimulator. The electronic subassembly 110 provides theelectronics used to operate the stimulator and generate the electricalpulses at the electrodes 154 to produce stimulation of the body tissues.FIG. 12 illustrates one embodiment of components of the electronicsubassembly and associated units.

In the illustrated embodiment, a processor 204 is generally included inthe electronic subassembly 110 to control the timing and electricalcharacteristics of the stimulator. For example, the processor can, ifdesired, control one or more of the timing, frequency, strength,duration, and waveform of the pulses. In addition, the processor 204 canselect which electrodes can be used to provide stimulation, if desired.In some embodiments, the processor may select which electrode(s) arecathodes and which electrode(s) are anodes. In some embodiments withelectrodes disposed on two or more sides of the housing, the processormay be used to identify which electrodes provide the most usefulstimulation of the desired tissue. This process may be performed usingan external programming unit, as described below, that is incommunication with the processor 204.

Any processor can be used and can be as simple as an electronic devicethat produces pulses at a regular interval or the processor can becapable of receiving and interpreting instructions from an externalprogramming unit 208 that allow modification of pulse characteristics.In the illustrated embodiment, the processor 204 is coupled to areceiver 202 which, in turn, is coupled to the optional antenna 124.This allows the processor to receive instructions from an externalsource to direct the pulse characteristics and the selection ofelectrodes, if desired.

In one embodiment, the antenna 124 is capable of receiving signals(e.g., RF signals) from an external telemetry unit 206 which isprogrammed by a programming unit 208. The programming unit 208 can beexternal to, or part of, the telemetry unit 206. The telemetry unit 206can be a device that is worn on the skin of the user or can be carriedby the user and can have a form similar to a pager or cellular phone, ifdesired. As another alternative, the telemetry unit may not be worn orcarried by the user but may only be available at a home station or at aclinician's office. The programming unit 208 can be any unit that canprovide information to the telemetry unit for transmission to thestimulator. The programming unit 208 can be part of the telemetry unit206 or can provide signals or information to the telemetry unit via awireless or wired connection. One example of a suitable programming unitis a computer operated by the user or clinician to send signals to thetelemetry unit.

The signals sent to the processor 204 via the antenna 124 and receiver202 can be used to modify or otherwise direct the operation of thestimulator. For example, the signals may be used to modify the pulses ofthe stimulator such as modifying one or more of pulse duration, pulsefrequency, pulse waveform, and pulse strength. The signals may alsodirect the stimulator to cease operation or to start operation or tostart charging the battery. In other embodiments, the electronicsubassembly 110 does not include an antenna 124 or receiver 202 and theprocessor operates as programmed.

Optionally, the stimulator may include a transmitter (not shown) coupledto the processor and antenna for transmitting signals back to thetelemetry unit 206 or another unit capable of receiving the signals. Forexample, the stimulator may transmit signals indicating whether thestimulator is operating properly or not or indicating when the batteryneeds to be charged. The processor may also be capable of transmittinginformation about the pulse characteristics so that a user or cliniciancan determine or verify the characteristics.

The optional antenna 124 can have any form. In one embodiment, theantenna comprises a coiled wire that is wrapped at least partiallyaround the electronic subassembly within or on the housing.

Any method of manufacture of the components of the system forstimulation can be used. For example, the power source and antenna canbe manufactured as described in U.S. Patent Application Publication No.2004/0059392. These components can then be placed inside the housing(or, alternatively, the housing can be formed, e.g., molded, around thecomponents).

The above specification, examples and data provide a description of themanufacture and use of the composition of the invention. Since manyembodiments of the invention can be made without departing from thespirit and scope of the invention, the invention also resides in theclaims hereinafter appended.

What is claimed as new and desired to be protected by Letters Patent of the United States is:
 1. An implantable lead for a stimulation device comprising: an implantable planar array of electrodes comprising at least two columns of electrodes, at least one of the columns comprising a plurality of electrodes, each electrode having a front surface to be placed in contact with a tissue, a back surface opposite the front surface, and a sidewall extending away from the back surface and defining a cavity bounded by the sidewall and back surface; a plurality of conductors, wherein a distal portion of each of the conductors is attached to the back surface of a respective one of the electrodes; a carrier formed around the array of electrodes but not completely covering the front surface or back surface of the electrodes, wherein the carrier comprises a carrier material and maintains an arrangement of the electrodes; and a biocompatible material disposed over, and in contact with, the carrier, the distal portions of the plurality of the conductors, and the back surfaces of the electrodes, the biocompatible material filling the cavity defined by each electrode, wherein the carrier and the biocompatible material are different and the carrier and biocompatible material form a paddle containing the at least two columns of electrodes with the biocompatible material forming at least an exterior bottom surface of the paddle.
 2. The lead of claim 1, wherein the carrier and the biocompatible material have a different durometer.
 3. The lead of claim 1, wherein the electrodes have a concave shape.
 4. The lead of claim 1, further comprising an adhesive disposed on a portion of at least one of the conductors and a corresponding one of the electrodes and configured and arranged to provide stress relief to an attachment between the conductor and the corresponding one of the electrodes.
 5. The lead of claim 4, wherein the adhesive is selected from the group consisting of silicones, epoxies, and acrylics.
 6. The lead of claim 1, wherein the biocompatible material is electrically insulative.
 7. A method of making the lead of claim 1, the method comprising: forming a planar array of electrodes in a pre-determined arrangement by positioning the electrodes in a carrier mold, wherein the array of electrodes comprises at least two columns of electrodes, at least one of the columns comprising a plurality of electrodes; molding a carrier around the array of electrodes to maintain the arrangement by inserting a carrier material into the carrier mold such that the carrier material molds around the electrodes, wherein the electrodes are retained in the carrier by the carrier material; coupling a plurality of conductors to the plurality of electrodes after molding the carrier around the array of electrodes; and disposing a biocompatible material over at least a portion of the carrier after coupling the plurality of conductors to the plurality of electrodes to form an array body comprising the array, the carrier, and the biocompatible material, wherein the array body has a form of a paddle with the at least two columns of electrodes.
 8. The method of claim 7, wherein the carrier mold comprises electrode positioning features.
 9. The method of claim 8, wherein the electrode positioning features are depressions in the carrier mold.
 10. The method of claim 7, further comprising applying an adhesive to an end of at least one of the plurality of conductors that is coupled to a one of the plurality of electrodes.
 11. The method of claim 7, wherein disposing the biocompatible material comprises molding the biocompatible material over at least a portion of the carrier.
 12. The method of claim 7, wherein disposing the biocompatible material comprises disposing the biocompatible material over substantially all of at least one surface of the carrier.
 13. The method of claim 7, wherein disposing the biocompatible material comprises disposing the biocompatible material around an end portion of each of the plurality of conductors, wherein the end portion is coupled to a one of the plurality of electrodes.
 14. The method of claim 7, wherein each of the electrodes comprises opposing planar front and back surfaces, wherein the front surface is exposed in the lead and a conductor is attached to the back surface, and wherein molding a carrier comprises molding the carrier between the electrodes leaving the front and back surfaces substantially uncovered.
 15. The method of claim 7, wherein the plurality of electrodes each comprise a front surface to be placed in contact with a tissue and a back surface opposite the front surface, and wherein coupling a plurality of conductors to the plurality of electrodes comprises coupling a distal portion of each of the plurality of conductors to the back surface of a respective one of the plurality of electrodes.
 16. A system for stimulation comprising: an electronic subassembly; an implantable lead comprising a planar array of electrodes comprising at least two columns of electrodes, at least one of the columns comprising a plurality of electrodes, wherein each electrode has a front surface to be placed in contact with a tissue, a back surface opposite the front surface, and a sidewall extending away from the back surface and defining a cavity bounded by the sidewall and back surface; a carrier comprising a carrier material and formed around the array of electrodes but not completely covering the front surface or back surface of the electrodes, wherein the carrier maintains an arrangement of the electrodes; a plurality of conductors, wherein a distal portion of each of the conductors is attached to the back surface of a respective one of the electrodes, and wherein the conductors couple the electrodes to the electronic subassembly; and a biocompatible material disposed over, and in contact with, the carrier, the distal portions of the plurality of conductors, and the back surfaces of the electrodes, the biocompatible material filling the cavity defined by each electrode, wherein the carrier and the biocompatible material are different and wherein the carrier and biocompatible material form a paddle containing the at least two columns of electrodes with the biocompatible material forming at least an exterior bottom surface of the paddle.
 17. The system for stimulation of claim 16, wherein the carrier and the biocompatible material have a different durometer.
 18. The system for stimulation of claim 16, wherein the biocompatible material is electrically insulative. 